1. Field of the Invention
This invention relates to a Fe—Ni based permalloy suitable for use in a magnetic head, a magnetic shielding material, an iron core of a transformer or the like and having excellent magnetic properties and a method of producing the same as well as a cast slab.
2. Description of Related Art
As the Fe—Ni based high magnetic permeability alloy or so-called permalloy, there are usually typified PB material (40–50 wt % Ni), PC material (70–85 wt % Ni—Mo—Cu), PD material (35–40 wt %-Ni—Fe),and the like, which are defined according to JIS C2531. Among these alloys, the PB material is mainly used in applications utilizing the characteristic that saturated magnetic flux density is large, such as stator in a watch, pole piece in an electromagnetic lens and the like, while the PC material is used as a high sensitivity transformer or a magnetic shielding material at a high frequency zone utilizing an excellent permeability. Among these alloys, it is designed to cope with applications such as a magnetic head, a shield case and the like by adding an additional element such as Nb, Cr or the like to provide the abrasion resistance and corrosion resistance (for example, JP-A-60-2651).
As another example of improving the properties of these alloys, JP-A-62-142749 and the like disclose that the permeability and the punching property are improved by adjusting impurity elements such as S, O and the like. Recently, the movement from PC material to PB material or from PB material to PD material is observed for reducing the cost, or there is adopted a method of supplementing for the lack of material properties by designing a fabricator.
In the material makers, therefore, it is strongly noticed to develop materials such as PB material having properties corresponding to those of PC material or PD material having properties corresponding to those of PB material. This increases a degree of freedom in the design of fabricator and hence is effective to give products having higher performances to markets.